Fix a small leak in CPDF_DataAvail::CheckTrailer().
Fix a small leak in CPDF_DataAvail::CheckTrailer().

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1278713003 .

DrAlexx/pdfium,DrAlexx/pdfium,azunite/libpdfium,andoma/pdfium,DrAlexx/pdfium,was4444/pdfium,andoma/pdfium,was4444/pdfium,andoma/pdfium,azunite/libpdfium,azunite/libpdfium,was4444/pdfium,DrAlexx/pdfium,andoma/pdfium,was4444/pdfium,azunite/libpdfium